chrome/blink: Add functionality for in-product help for media elements.

third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp

Index: third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
diff --git a/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp b/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
index fc58f579134a097d1e2c9faeb4a6bdc1fa959e93..65b2fa0e913cd3297d13486deed390ac3bd6fbe8 100644
--- a/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
+++ b/third_party/WebKit/Source/modules/media_controls/elements/MediaControlDownloadButtonElement.cpp
@@ -6,6 +6,7 @@
 
 #include "core/InputTypeNames.h"
 #include "core/events/Event.h"
+#include "core/frame/LocalFrameClient.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLAnchorElement.h"
 #include "core/html/HTMLMediaElement.h"
@@ -14,7 +15,9 @@
 #include "core/page/Page.h"
 #include "modules/media_controls/MediaControlsImpl.h"
 #include "platform/Histogram.h"
+#include "platform/wtf/Functional.h"
 #include "public/platform/Platform.h"
+#include "services/service_manager/public/cpp/interface_provider.h"
 
 namespace blink {
 
@@ -88,14 +91,18 @@ bool MediaControlDownloadButtonElement::HasOverflowButton() const {
 void MediaControlDownloadButtonElement::SetIsWanted(bool wanted) {
   MediaControlInputElement::SetIsWanted(wanted);
 
-  if (!IsWanted())
+  if (!IsWanted()) {
+    DismissInProductHelp();

[mlamouri (slow - plz ping), 2017/07/25 17:29:08]

That code should no longer be here, you will have to rebase. Most likely, you
update the IPH state in ::UpdateShownState()

[Khushal, 2017/08/03 02:41:21]

Done.

     return;
+  }
 
-  DCHECK(IsWanted());
   if (!show_use_counted_) {
     show_use_counted_ = true;
     RecordMetrics(DownloadActionMetrics::kShown);
   }
+
+  // If the button is wanted, show IPH if possible.
+  MaybeDispatchInProductHelpTrigger();
 }
 
 DEFINE_TRACE(MediaControlDownloadButtonElement) {
@@ -132,4 +139,77 @@ void MediaControlDownloadButtonElement::RecordMetrics(
   download_action_histogram.Count(static_cast<int>(metric));
 }
 
+void MediaControlDownloadButtonElement::MaybeDispatchInProductHelpTrigger() {
+  // Is showing in-product help enabled?
+  if (!MediaElement().GetDocument().GetSettings() ||
+      !MediaElement()
+           .GetDocument()
+           .GetSettings()
+           ->GetMediaDownloadInProductHelpEnabled()) {
+    return;
+  }
+
+  // Restrict showing in-product help to once per element.
+  if (media_download_in_product_trigger_observed_)
+    return;
+
+  // Download in-product-help is only shown for videos.
+  if (!MediaElement().IsHTMLVideoElement())
+    return;

[mlamouri (slow - plz ping), 2017/07/25 17:29:08]

Looking at this and what follows, I wonder if it would make sense to have an
object for IPH instead of MediaControlDownloadButton receiving calls to deal
with the IPH. If the object was owned by the MediaControls, it could only be
created when needed (ie. for video element, when the setting was on). It would
also simplify the logic as MediaControls would makes the call to the IPH wrapper
instead of calling methods on MediaControlDownloadButton to update the IPH. I
think the only issue is that the MediaControlDownloadButton visibility would
need to notify the IPH. Maybe the object could be accessible via a getter? WDYT?

[Khushal, 2017/08/03 02:41:21]

We can move this code to a seperate class owned by MediaControlsImpl but it
needs to poke at some internals of the controls.

1) Whether the download button IsWanted and CanFit. Since the dispatch trigger
comes when the pause state changes or download button state changes, it needs to
know that all the conditions are satisfied.

2) Also needs the download button to compute its position.

3) Whether the panel IsWanted. If it was hidden using Hide(), then we don't show
the IPH.

4) When the IPH is dismissed from the browser, it needs to poke the controls to
start the hide timer.

I'm not sure if you'd prefer to expose all of this from the controls? Or may be
it would be cleaner to restore this in the controls and just add one method on
MediaControlsImpl that the download button can call:

void MayBeDispatchDownloadInProductHelp()

from UpdateShownState.

+
+  // If showing the controls is disabled, we can't make them visible to show the
+  // in-product-help.
+  if (!static_cast<MediaControlsImpl&>(GetMediaControls()).CanShow())
+    return;
+
+  // If the download option is not available for this video, no need to show
+  // anything.
+  if (!IsWanted())
+    return;
+
+  // Restrict showing in-product-help to when the video is playing.
+  if (MediaElement().paused())
+    return;
+
+  if (!MediaElement().GetDocument().GetFrame())
+    return;
+
+  // If the button is not in the viewport, don't show the in-product-help.
+  IntRect button_rect = VisibleBoundsInVisualViewport();
+  if (button_rect.IsEmpty())
+    return;
+
+  media_download_in_product_trigger_observed_ = true;
+  media_in_product_help_ =
+      WTF::MakeUnique<mojom::blink::MediaDownloadInProductHelpPtr>();
+  MediaElement()
+      .GetDocument()
+      .GetFrame()
+      ->Client()
+      ->GetInterfaceProvider()
+      ->GetInterface(mojo::MakeRequest(media_in_product_help_.get()));
+  media_in_product_help_->set_connection_error_handler(ConvertToBaseCallback(
+      WTF::Bind(&MediaControlDownloadButtonElement::DismissInProductHelp,
+                WrapWeakPersistent(this))));
+
+  // MaybeShow should always make the controls visible since we early out if
+  // CanShow is false for the controls.
+  GetMediaControls().MaybeShow();
+  DCHECK(GetMediaControls().IsVisible());
+  (*media_in_product_help_)->ShowInProductHelpWidget(button_rect);
+}
+
+void MediaControlDownloadButtonElement::DismissInProductHelp() {
+  if (!media_in_product_help_)
+    return;
+
+  media_in_product_help_.reset();
+  static_cast<MediaControlsImpl&>(GetMediaControls())
+      .StartHideMediaControlsIfNecessary();
+}
+
+bool MediaControlDownloadButtonElement::IsShowingInProductHelp() const {
+  return !!media_in_product_help_;
+}
+
 }  // namespace blink